Mr Dyball believes the investigation into his activities shows a double standard in the Federal Government's position.

"You [the Government] say we can't fight for them [the YPG], but yet you fund them," he said.

"You'll air strike for them. You'll aid them. So how is it OK for you to aid them and I can't aid them?"

'This was something I felt had to be done'

Mr Dyball became interested in the conflict in Syria three years ago and became increasingly agitated by the atrocities he saw committed by Islamic State.

"The main drive for me to go over there was just to help the children and the people," he said.

"I was just sick of seeing women and children beheaded, raped, it just didn't sit well with me.

"I was never originally going over to fight or nothing like that. I was just going to go help in hospitals and shit like that.

"I probably thought about it for well over a year — never said a word to anyone, just did it in silence, nothing on your home computer or anything like that, burner phones, libraries, things like that."

In a statement to 7.30, a spokesman for Attorney-General George Brandis said: "The Australian Government has, for a number of years, strongly and consistently discouraged Australians from travelling to conflict zones such as Syria and Iraq to participate in hostile activities.

"It is dangerous, it puts others' lives at risk, and it may constitute a criminal offence.

"Australian security and law enforcement agencies manage individuals of security concern on a case-by-case basis.

"These laws do not differentiate between various non-government militia groups involved in foreign conflicts."